Abstract
The objective of the present study was to prepare a stable iv injectable formulation of ascorbic acid and α-tocopherol in preventing the cerebral ischemia. Different niosomal formulations were prepared by Span and Tween mixed with cholesterol. The physicochemical characteristics of niosomal formulations were evaluated in vitro. For in vivo evaluation, the rats were made ischemic by middle cerebral artery occlusion model for 30 min and the selected formulation was used for determining its neuroprotective effect against cerebral ischemia. Neuronal damage was evaluated by optical microscopy and transmission electron microscopy. The encapsulation efficiency of ascorbic acid was increased to more than 84% by remote loading method. The cholesterol content of the niosomes, the hydrophilicity potential of the encapsulated compounds, and the preparation method of niosomes were the main factors affecting the mean volume diameter of the prepared vesicles. High physical stability of the niosomes prepared from Span 40 and Span 60 was demonstrated due to negligible size change of vesicles during 6 months storage at 4–8°C. In vivo studies showed that ST60/Chol 35 : 35 : 30 niosomes had more neuroprotective effects against cerebral ischemic injuries in male rats than free ascorbic acid.
Highlights
Cerebral ischemia is the third leading cause of deaths in the United States [1]
Encapsulation efficiencies (EE) in all studied formulations are shown in Table 2. αTocopherol had often higher EE% than ascorbic acid, which is clearly due to its hydrophobic nature and its intercalating in lipophilic core of surfactant bilayers [27]
For confirmation of our results in light microscopy, we studied the ultrastructure of the pyramidal neurons in the cortex of male rats using transmission electron microscope (TEM)
Summary
Cerebral ischemia is the third leading cause of deaths in the United States [1]. In patient with acute cerebral ischemia, thrombolysis therapy could reduce death after ischemia [2]. It is reported that free radical oxygen has potential role in neural cell damage in ischemia-reperfusion disorders [5, 6] Exogenous antioxidant such as ascorbic acid (vitamin C), α-tocopherol (vitamin E), and β-carotene can be effective on neuronal cell protection due to the effect of reactive oxygen species (ROS) on neuronal cell damages and fast consumption of endogenous scavenging antioxidants [5, 7]. Their effectiveness depends on their ability for transporting through the blood brain barrier (BBB) [8].
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